Continuous impregnation and digestion apparatus for the production of wood pulp



2-, FIG.1.

y 2 1967' u. LOWGREN ETAL 3,332,836

CONTINUOUS IMPREGNATION AND DIGESTION APPARATUS FOR THE PRODUCTION OFWOOD PULP Filed Aug. 28, 1964 4 Sheets-Sheet l y 25, 1967' u. LOWGRENETAL 3,332,836

CONTINUOUS IMPREGNATION AND DIGESTION APPARATUS FOR THE PRODUCTION OFWOOD PULP Filed Aug. 28, 1964 4 Sheets-Sheet 2 INVENTOR, U50 A0", ra: Trb// arj y 1967 u. LOWGREN ETAL1 3,332,836

CONTINUOUS IMPREGNATION AND DIGESTION APPARATUS FOR THE PRODUCTION OFWOOD PULP Filed Aug. 28, 1964 4 Sheets-Sheet 5 FIG.3. 46

AW 9w BY dfiiforn gy u. LOWGREN ETAL A 3,332,836 CONTINUOUS IMPREGNATIONAND DIGESTION APPARATUS July 25, 1967 FOR THE PRODUCTION OF WOOD PULP 4Sheets-Sheet 4 Filed Aug. 28, 1964 F i G 6.

United States Patent CONTINUOUS IMPREGNATION AND DIGESTION APPARATUS FORTHE PRODUCTION OF WOOD PULP Uno Lowgren, New Canaan, Conn., and Eric T.Kollberg, Port Chester, N.Y., assignors to American Defibrator, Inc.,New York, N.Y., a corporation of New York Filed Aug. 28, 1964, Ser. No.392,877 4 Claims. (Cl. 162-237) This invention relates to the productionof wood pulp from wood chips, sawdust and other ligno-cellulose materialand has for one of its objects the provision of an apparatus of thiskind by which the rapid and continuous production of the wood pulp isobtained.

It is an object of the invention to provide an apparatus by means ofwhich the sawdust or other wood particles are delivered from a number ofhoppers or other sources of supply into separate wetting tubes to whichthe white liquoris provided from cyclone means. In the wetting tubeswetting and thorough mixing and steaming of the wood and liquor takesplace, resulting in good pulp quality. The mixed material is thenconveyed from each of the wetting tubes to separate rotary feeders ofthe socalled volumetric type from which the material is delivered into across feed tube at a predetermined rate of feed and which tube extendsbetween and connects with the outlets of the rotary, feeders. Such crosstube contains screw feed means which is operative to move the materialtoward its outlet, centrally located on the tube and between thefeeders, and from which outlet the material passes successively througha plurality of superposed digester tubes wherein a constant steampressure is maintained and where the cooking of the material is carriedout. At the outlet of the lowermost digester tube the cooked sawdust,then in pulp condition, is brought to a sluicing valve system whichdischarges the pulp into a blow tank at atmospheric pressure.

With these and other objects to be hereinafter set forth in view, I havedevised the arrangement of parts to be described and more particularlypointed out in the claims appended hereto.

In the accompanying drawings, wherein an illustrative embodiment of theinvention is disclosed,

FIG. 1 is an elevational view of an apparatus for the production of woodpulp, constructed according to the invention;

FIG. 2 is a sectional view, taken substantially on the line 22 of FIG.1, looking in the direction of the arrows;

FIG. 3 is a continuation, in an enlarged scale, of a part of the lowerportion of FIG. 1;

FIG. 4 is a top plan view of the reciprocating sluice valves shown inFIG. 3;

FIG. 5 is a sectional view, taken substantially on the line 55 of FIG.1, looking in the direction of the arrows, and

FIG. 6 is a sectional view, taken substantially on the line 66 of FIG.1, looking in the direction of the arrows, and with some parts, whichare duplicates of others, shown in dotted lines to simplifyillustration.

The material to 'be treated, such as for example sawdust, wood chips orother ligno-cellulose material is supplied from two hoppers or bins 1and is fed therefrom by means of a volumetric feeder 2 which includes adelivery tube 3 containing a feeding element rotated by a sprocket 4from suitable driving means. From the tube 3, the sawdust or othermaterial is fed to a pair of wetting tubes 5, each containing a rotativespiral feeder which moves the material in the direction of the arrow inFIG. 1.

3,332,836 Patented July 25, 1967 Each volumetric feeder includes aU-shaped trough 8 containing two feed screws 9 (FIG.- 6) and by varyingthe speed of avariable speed motor which drives the screws throughsprocket 4, the sawdust can be metered volumetrically. As shown indotted lines in FIG. 6, the

mechanism described is duplicated as indicated at 10 so there areactually two wetting tubes, each having its own feeder. Each of thewetting tubes 5 consists of a trough 11 provided interiorly with ahorizontal conveyor screw. In each of the wetting tubes the sawdust ismixed with white liquir. The liquor and water are mixed in a cyclonemixer 12 and the wetting tubes are each provided with several steaminlets in order to preheat the sawdust while it is being mixed with thewhile liquor. A heat sensing device is mounted in the top cover of eachof the wetting tubes 5 and the temperature of the sawdust can becontrolled within a wide range from a suitable control panel.

The wetting tubes 5 each discharges the mixed sawdust and liquor througha conical throat 12a into a feed hopper 13, from which the sawdust isdischarged into a rotaryfeeder 14a. The hopper 13 is cylindrical inshape, having a conical bottom 14 and is provided with a vertical paddlescrew driven by suitable drive means operating through sprocket 15.

The rotary feeders, which are of known construction, consist essentiallyof a pocketed feeder 16 mounting in a housing 17 and having its shaft 60carrying a sprocket 61 driven from a suitable motor source. The rotor ofthe feeder is provided with a number of pockets, usually six, which arefilled with sawdust from the hopper 13 as they pass the inlet port ofthe housing 17. As the rotor 16 revolves, the pockets filled withsawdust, pass the outlet port of the housing 17 and the sawdust fallsout of the pockets of the rotor. To aid in the discharge of the sawdustfrom the pockets, there are steam jets directed toward the pockets. Asthe pockets are being emptied of sawdust they are filled with steam. Itis therefore important that the pockets be vented before they arrive infront of the inlet opening of the housing 17. For this purpose a blowline 18 is connected between the rotary feeder and the cyclone 12.

The cross conveyor 20, located between and below the two rotary feedersis a pressurized tubular vessel preferably made from carbon steel cladwith stainless steel. The cross conveyor 20 receives the sawdust fromthe rotary feeders 14a. A conveyor screw 22 contained within the crossconveyor, has one half of it provided with left hand helical flights andits other half provided with right hand flights and it thus conveys thesawdust from the two feeders 14a toward the center of the vessel 21 to acentral outlet 65 where the sawdust falls by gravity into the uppermosthorizontally-supported, pressurized digester tube 23.

The cross conveyor screw 22 is driven by a suitable mot-or and chainthrough sprocket 24 (FIG. 5). On top of the cross conveyor are providedflanges 25, 26 for steam lines and liquor lines.

The flow of the sawdust through the apparatus is indicated by arrows inFIG. 1. Therein it will be noted that the horizontal digester tube 23receives the sawdust at one end, through inlet 27 and carries it bymeans of an internal feed screw through the digester tube 23 in thedirection of the arrow appearing on the digester tube. The feed screwwithin the tube 23 is preferably provided with interrupted flights andits shaft rides on two greaselubricated antifriction pillow blockbearings 28, both located on the outside of the tube 23. The digesterfeed screw contained within the digester tube 23, is driven by asprocket 29 from a chain extending from a suitable motor drive.

After passing through the digester tube 23, the sawdust then dischargesthrough vertical outlet 30 into the connected inlet 31a of a seconddigester tube 31 located below the first tube 23. Said tube 31 is apressurized vessel and is substantially similar to the tube 23. The feedscrew of the tube 31 is supported in the bearings 32 and the sprocket33, mounted on the shaft of the feed screw drives the feed screw throughsuitable drive means from a motor. Means is provided for maintaining aconstant steam pressure in this digester tube as well as in all of theother digester tubes.

The sawdust is fed through the digester tube 31 toward the left asviewed in FIG. 1 or in the direction of the arrows appearing on the tube31, until the sawdust reaches the outlet 34 and it then passestherethrough into the connected inlet 35 to enter the third digestertube 36. Tube 36 is a pressurized vessel and is similar to digester tube31. This tube has its internal feed screw supported by the bearings 37and the sprocket 38 carried on the shaft of the screw is driven by asuitable motor through chain drive. i

The digester tube 36 discharges the sawdust through outlet 39 into aconnected outlet 40 leading into the fourth or last digester tube 41.This tube is similar to the others and is a pressurized vessel. It hasits internal feed screw supported by the bearings 42 and the shaftthereof carries a sprocket 43 driven by chain from a motor.

The several digester tubes are supported in the superposed relationshipshown in the drawings by means of reinforced framework disclosedgenerally at 44.

After passing through the lowermost digester tube 41 in the direction ofthe arrow shown thereon, the sawdust then in pulp form, passes out ofthe tube 41 by way of the outlet 45 to enter the inlet 46 of a screwdischarger generally indicated at 47 and shown more clearly in FIGS. 3and 4. Said discharger is in the form of a pressurized vessel 48containing a screw feeder 49 having its shaft 50 supported in thebearings 51 and carrying a drive sprocket 52 driven by chain from asuitable power source. A gate valve is provided at the bottom of thedischarger to draw off any condensate water that will collect on theinside of the digester tubes during the heating-up period.

Leading from the opposite sides of the screw discharger are tubes 53, 54that extend to reciprocating valves 55 that are employed to dischargethe pulp from the pressurized digester tubes to a blow tank, not shown,but one which is under atmospheric pressure. The reciprocating valvesare of the type which operate on the sluicing principle. Thereciprocating valves are equipped with cylinders and solenoid valves sothat if there is a tendency to plug, the valves can be operated remotelyfrom a control panel located in a control room.

By means of the continuous digester described, the continuous pulping ofwood chips, sawdust or other lignocellulose material is effectivelyobtained. The raw material, which can be sawdust, chips or otherligno-cellulose material, and which is for convenience herein mentionedas sawdust, is delivered from the hoppers 1 to be soaked in the whiteliquor in the wetting and steaming tubes which also provides for athorough mixing of the sawdust with the liquor and which is importantfor the securement of good pulp quality. The liquor-impregnated sawdustis then conveyed to the two rotary feeders 14a which deliver the sawdustto the central outlet 65 of the cross delivery tube and which deliversthe material into the uppermost digester tube 23, wherein a constantsteam pressure is maintained and wherein the cooking of the materialtakes place. The material is transported from one of the digester tubesto the others until it has progressed through all of them. The conveyorscrews operating in the several digester tubes are rotated at controlledspeeds. At the end of the cooking procedure, which usually takes fromtwenty to thirty minutes, the cooked sawdust, which by this time hasbecome pulp, is brought to the valves 55, which as previously explainedare of the sluice type, and act to discharge the pulp into a blow tankat atmospheric pressure.

Having thus described a single embodiment of the invention, it isobvious that the same is not tobe restricted thereto, but is broadenough to cover all structures coming within the scope of the annexedclaims.

What is claimed is:

1. An apparatus for the production of wood pulp comprising:

a plurality of hoppers from which wood particles are fed, each of saidhoppers having an outlet;

a wetting vessel for each hopper, which vessel is connected to saidhopper outlet for receiving wood particles therefrom;

a cyclone mixer for each wetting vessel connected to said vessel fordelivering liquor to mix with the wood particles therein;

each wetting vessel containing a means for feeding and agitating themixture, and having an outlet connected to and discharging into amixture feed hopper;

each of said mixture feed hoppers having an outlet connected to anddischarging into a rotary feeder, each of said rotary feeders havingfeed pockets and an outlet;

a cross conveyor extending between and connecting said rotary feederoutlets, said cross conveyor having a discharge outlet, said conveyordischarge outlet being between said feeder outlets and being connectedto a digester tube means;

said digester tube means comprising a plurality of superposed,substantially horizontal digester tubes, an outlet of each tube beingconnected to an inlet of the tube below so that the path followed bysaid mixture is sinusoidal; and

valve means connected to an outlet of the lowermost of the digestertubes.

2. An apparatus for the production of wood pulp comprising:

a plurality of hoppers from which wood particles are fed, each of saidhoppers having an outlet;

a wetting vessel for each hopper, which vessel is connected to saidhopper outlet for receiving wood par ticles therefrom;

a cyclone mixer for each wetting vessel connected to said vessel fordelivering liquor to mix with the wood particles therein;

each wetting vessel containing a means for feeding and agitating themixture, and having an outlet connected to and discharging into amixture feed hopper;

each of said mixture feed hoppers having an outlet connected to anddischarging into a rotary feeder, each of said rotary feeders havingfeed pockets and an outlet;

:1 cross conveyor extending between and connecting said rotary feederoutlets, said cross conveyor having a discharge outlet, said crossconveyor discharge outlet being between said feeder outlets and beingconnected to a digester tube means;

said digester tube means comprising a plurality of superposed,substantially horizontal digester tubes, an outlet of each tube beingconnected to an inlet of the tube below so that the path followed by thesaid mixture is sinusoidal;

valve means connected to an outlet of the lowermost of the digestertubes; and

blow tube means connecting each rotary feeder to said cyclone, wherebysteam and gases are removed from the pockets of said rotary feeder.

3. An apparatus for the production of wood pulp comprising:

a plurality of hoppers from which wood particles are.

fed, each of said hoppers having an outlet;

a wetting vessel for each hopper, which vessel is connected to saidhopper outlet for receiving wood particles therefrom;

a cyclone mixer for each wetting vessel connected to said vessel fordelivering liquor to mix with the a wetting vessel which is connected tosaid hopper outlet for receiving wood particles therefrom;

a cyclone mixer connected to said vessel for delivering liquor to mixwith the wood particles therein;

5 said wetting vessel containing a means for feeding and wood particlestherein; agitating the mixture, and having an outlet connected eachwetting vessel containing a means for feeding to and discharging into amixture feed hopper;

and agitating the mixture, and having an outlet consaid mixture feedhopper having an outlet connected nected to and discharging into amixture feed to and discharging into a rotary feeder, said rotaryhopper; 10 feeder having feed pockets and an outlet; each of saidmixture feed hoppers having an outlet blow tube means connecting saidrotary feeder to said connected to and discharging into a rotary feeder,cyclone, whereby steam and gases are removed from each of said rotaryfeeders having feed pockets and the pockets of said rotary feeder; anOutlet; a delivery tube means connected to said rotary feeder a crossdelivery tube extending between and connect" outlet, said delivery tubemeans containing means by ing said rotary feeder outlets, said tubehaving a Whichthe materians mixed and discharge outlet at substantiallythe center thereof, a plurality of vertically Spaced digester tubes, ana nd.feed means h by Whlch matenal 15 let of each tube being connectedto an inlet of the livered toward said center outlet, said center outlettube below so that the Path followed by Said being connected to adigester tube means; said d' ester tube means corn risin a luralit oftum 1s Smusoldal and P g p a valve means connected to the last of saiddigester superposed, substantially horizontal digester tubes, h f th flf d 1 there an outlet of each tube being connected to an inlet w es orComm mg 6 OW 0 W00 pup of the tube below so that the path followed bysaid mixture is sinusoidal; References Cited valve means connected to anoutlet of the lowermost UNITED STATES PATE TS of said digester tubes;and 2,993,537 7/1961 Green 162-237 blow tube means connecting eachrotary feeder to said 3,007,839 11/1961 Richter 1 c clone, whereby steamand gases are removed from tl ie pockets of said rotary feeder. FOREIGNPATENTS 4. An apparatus for the production of wood pulp com- 382,002 3/1963 Japan.

prising:

a hopper from which wood particles are fed, said hopper having anoutlet;

S. LEON BASHORE, Primary Examiner.

1. AN APPARATUS FOR THE PRODUCTION OF WOOD PULP COMPRISING: A PLURALITYOF HOPPERS FROM WHICH WOOD PARTICLES ARE FED, EACH OF SAID HOPPERSHAVING AN OUTLET; A WETTING VESSEL FOR EACH HOPPER, WHICH VESSEL ISCONNECTED TO SAID HOPPER OUTLET FOR RECEIVING WOOD PARTICLES THEREFROM;A CYCLONE MIXER FOR EACH WETTING VESSEL CONNECTED TO SAID VESSEL FORDELIVERING LIQUOR TO MIX WITH THE WOOD PARTICLES THEREIN; EACH WETTINGVESSEL CONTAINING A MEANS FOR FEEDING AND AGITATING THE MIXTURE, ANDHAVING AN OUTLET CONNECTED TO AND DISCHARGING INTO A MIXTURE FEEDHOPPER; EACH OF SAID MIXTURE FEED HOPPERS HAVING AN OUTLET CONNECTED TOAND DISCHARGING INTO A ROTARY FEEDER, EACH OF SAID ROTARY FEEDERS HAVINGFEED POCKETS AND AN OUTLET; A CROSS CONVEYOR EXTENDING BETWEEN ANDCONNECTING SAID ROTARY FEEDER OUTLETS, SAID CROSS CONVEYOR HAVING ADISCHARGE OUTLET, SAID CONVEYOR DISCHARGE OUTLET BEING BETWEEN SAIDFEEDER OUTLETS AND BEING CONNECTED TO A DISCHARGE TUBE MEANS; SAIDDIGESTER TUBE MEANS COMPRISING A PLURALITY OF SUPERPOSED, SUBSTANTIALLYHORIZONTAL DIGESTER TUBES, AN OUTLET OF EACH TUBE BEING CONNECTED TO ANINLET OF THE TUBE BELOW SO THAT THE PATH FOLLOWED BY SAID MIXTURE ISSINUSOIDAL; AND VALVE MEANS CONNECTED TO AN OUTLET OF THE LOWERMOST OFTHE DIGESTER TUBES.